Modern wheat cultivars have greater root nitrogen uptake efficiency than old cultivars

Abstract

The availability of nitrogen (N) contained in crop residues for a following crop may vary with cultivar, depending on root traits and the interaction between roots and soil. We used a pot experiment to investigate the effects of six spring wheat (Triticum aestivum L.) cultivars (three old varieties introduced before mid last century and three modern varieties) and N fertilization on the ability of wheat to acquire N from maize (Zea mays L.) straw added to soil. Wheat was grown in a soil where 15N‐labeled maize straw had been incorporated with or without N fertilization. Higher grain yield in three modern and one old cultivar was ascribed to preferred allocation of photosynthate to aboveground plant parts and from vegetative organs to grains. Root biomass, root length density and root surface area were all smaller in modern than in old cultivars at both anthesis and maturity. Root mean diameter was generally similar between modern and old cultivars at anthesis but was greater in modern than in old cultivars at maturity. There were cultivar differences in N uptake from incorporated maize straw and the other N sources (soil and fertilizer). However, these differences were not related to variation in the measured root parameters among the six cultivars. At anthesis, total N uptake efficiencies by roots (total N uptake per root weight or root length) were greater in modern than in old cultivars within each fertilization level. At maturity, averaged over fertilization levels, the total N uptake efficiencies by roots were 292−336 mg N g−1 roots or 3.2−4.0 mg N m−1 roots for three modern cultivars, in contrast to 132−213 mg N g−1 roots or 0.93−1.6 mg N m−1 roots for three old cultivars. Fertilization enhanced the utilization of N from maize straw by all cultivars, but root N uptake efficiencies were less affected. We concluded that modern spring wheat cultivars had higher root N uptake efficiency than old cultivars.

Effect of Different Combinations of Phosphorus and Nitrogen Fertilization on Arbuscular Mycorrhizal Fungi and Aphids in Wheat

“…The response of wheat growth to soil nutrient levels has received much attention. Many studies have shown that N is a major limiting factor in crop production, with a positive relationship between wheat yield and N amount [63][64][65]. Our results are consistent with these studies, and we found that aboveground biomass and yield increased with increasing N. Such effects of N on wheat yield are reasonable, because increasing N levels significantly increase the grain count, the number of spikes, and the thousand-grain weight [66].…”

Improved Bread and Durum Wheat Cultivars Showed Contrasting Performances in N-Efficiency and N-Responsiveness

“…Gaju et al [14] also reported great variations among wheat genotypes ranging from 36% for "W300" to 53% for "Cordiale," and higher HI under low N (46%) compared with optimum N (43%), which support the present findings. Corroborating the current observation, Zhang et al [37] also reported that HI did not differ between N fertilized and unfertilized treatments but significantly varied among wheat cultivars that contrasted in N efficiency. In this study, HI showed weak correlation with grain yield under both low and optimum N (data not shown) as contrasted to Gaju et al [14], who attained positive linear relationships among genotypes between HI and grain yield under high N and low N conditions.…”

Climate Change Impact on Wheat Performance—Effects on Vigour, Plant Traits and Yield from Early and Late Drought Stress in Diverse Lines

“…A general understanding among Swedish growers is that old wheat varieties have a strong root growth, which contributes to their good performance during dry conditions, although scientific evidence for such a statement is lacking. However, in a recent study, a larger root system was observed in old wheat varieties than in modern wheat [ 34 ]. Furthermore, this large-to-small change in root biomass from old to modern wheat has been confirmed by several studies [ 35 , 36 , 37 ].…”